The present invention relates to a cartridge for a printing ribbon for a typewriter or other printer, for example of the type having a character-carrying disc, comprising a printing ribbon having a plurality of tracks which can be selected for the printing operation, a casing for the ribbon, a pair of terminal portions provided with guide elements between which an external run of the ribbon extends, the guide elements being movable relative to each other and with respect to the casing, for the selection of one of the tracks while maintaining uniform tension across the width of the ribbon.
Such a cartridge is known from EP No. 0 118 238, in which the terminal portions are oscillating arms and in which the guide elements are integral with the arms, which oscillate to move the selected track into a position in front of the character-carrying disc. The guide elements co-operate with two corresponding control cams which are fixed with respect to the casing and which modify the inclination of the guide elements during the oscillation movement of the arms from the viewing position to the various heights involved in track selection. The tension of the ribbon in its various working conditions is thus kept constant across the width of the ribbon. The use of this known cartridge is particlarly advantageous in machines of the type referred to as `aisywheel` machines in which the ribbon has a very small space between the platen roller and the daisywheel itself. However the cartridge suffers from the disadvantage of impairing vision in the region of the line of typing adjacent to the control cams for the guide elements.